Electric incandescent projection lamp



June 1967 c. F. O'NEILL ETAL 3,32

ELECTRIC INCANDESCENT PROJECTION LAMP Filed April 7, 1965 lnveTvtoT-s: Cbi F' f-ovd F. ONeiLL Lewis J. (Dorsey-c) b5 art/Q Their A torneg United States Patent 3,325,667 ELECTRIC INCANBESCENT PRGJECTZ'ON LAMP Clifford F. ONeill, Wiiloughby, and Lewis J. Corsaro, Cleveland Heights, Ohio, assignors to General Electric Company, a corporation of New York Fiied Apr. 7, 1965, Ser. No. 446,345 4 Claims. (Cl. 313-413) This invention relates generally to electric incandescent lamps, more particularly to projection lamps, and still more particularly to projection lamps incorporating an internal reflector.

There has been on the market a projection lamp which is particularly useful in movie projectors, for example, and which comprises a sealed tubular glass bulb containing a filament and an internal reflector having its light projection axis normal to the bulb axis and supported from support and lead-in wires extending into the bulb from a flat glass button-type stem at the end of the bulb. In order to provide a reflector of as large a size as possible for a given bulb diameter, it was cut away at its sides and was supported from a first pair of support wires with the mouth of the reflector in a plane extending substantially through the bulb axis. The said first pair of support wires were located in a plane parallel to that of the reflector mouth but offset a substantial distance therefrom and from the bulb axis. The reflector was provided at its bottom with a pair of widely spaced tabs or studs and was supported by L-shaped brace wires welded to respective tabs and support wires. For increased strength, an additional straight wire brace was welded across and between the said first pair of support wires. The reflector was additionally supported by an intermediate lead wire connected at one end to an inner lead wire at the apex of the reflector and at its other end to one of a second pair of support wires which also served as current lead-in conductors and which were located in a plane parallel to the plane of the first pair of support wires but at the opposite side f the bulb axis.

In spite of all this support structure, the reflector was subject to a considerable degree of sideward motion and, by application of sufficient force such as could readily occur in shipping the lamps, the reflector could strike the glass bulb and cause it to fracture. This action could occur even when the sides of the reflector were cut away sufficiently to leave a reflector width substantially less than the bulb diameter.

It is therefore an object of this invention to provide an improved support structure for the reflector of lamps of the type described above. Further objects include the provision of a more rugged construction, minimizing filament vibration, reducing material and labor costs, and providing improved optical performance.

In accordance with a primary aspect of the invention, the improved construction is achieved by offsetting the reflector in the bulb to bring its mouth into a plane virtually coincident with the plane containing the aforesaid first pair of support wire members, and providing means which also lie virtually in the said plane containing said first pair of support wire members, and effectively securing the reflector from spaced points at its lower end directly to both said first pair of support wire members. Such means may comprise, for example, a single wire brace which is secured at its ends to spaced points at the lower edge of the reflector and which also extends across and is secured at intermediate points thereon tc respective ones of said support wire members. Such means may also comprise tabs or stud members spaced apart at the lower edge of the reflector a distance corresponding to the spacing between said first pair of support wire members and secured directly thereto.

Further features and advantages of the invention will appear from the following detailed description of species thereof and from the drawing wherein:

FIGS. 1, 2 and 3 are front, side and rear elevation views, respectively, of a lamp comprising the invention; and

FIGS. 4 and 5 are front and side elevations, respectively, of another species of the invention.

Referring to FIGS. 1, 2 and 3, the lamp illustrated therein comprises a tubular gas filled glass bulb 1 having a neck portion 2 sealed to a flat circular button-type glass stem 3 (FIG. 2) through which are sealed a first pair of support Wire members 4 and 5 and a second pair of support wire members 6 and 7. The pairs of wire 4, 5 and 6, 7 are located in respective longitudinal planes parallel to and on opposite sides of the bulb axis A. Each of said Wires 4 to 7 actually consists of inner and outer sections of relatively heavy rigid wire such as nickel-iron alloy, and a short intermediate section 8 of for example Dumet (a copper sleeved nickel-iron core wire) each of which makes a hermetic seal with the glass stem 3 or, more specifically, with individual glass bosses 9 on said stem.

The bulb 1 also contains a filament 10 at the front of a concave reflector 11 which may be of any desired shape, such as ellipsoidal. In order to make the reflector of as large a diameter as possible and still fit into the bulb 1, it is cut away at the sides as shown at 12. The filament 10 is mounted between and across a pair of inner lead wires 13 and 14 which extend through passages in a ceramic insulator button 15 located in a slot at the apex of the reflector 11. The inner lead wire 13 is connected by a rigid intermediate lead wire portion 16 t0 the support Wire 6. The other inner lead wire 14 is, in the illustrated example, electrically connected through a ballast filament 17 and a fuse wire portion 18 to the support wire 7. The outer or external portions of support wires 6 and 7 thereby serve as current supply conductors or pins. The ceramic insulator 15 is clamped securely to the reflector 11 by crimping the reflector thereto. The said insulator 15 has an enlarged flange portion 19 (FIG. 2) at its inner end; thickened sections of the inner lead wires 13 and 1 are bent or crimped against respective ends of the insulator; and the intermediate rigid conductor 16 is welded to the outer end of inner lead wire 13 at the rear face of the insulator 15.

The lamp is also provided with a conventional sheet metal base 20 which is cemented to the bulb neck 2.

The reflector 11 may be made of sheet copper, plated with nickel and coated with vapor deposited aluminum or electrolytically deposited silver. As shown in FIGS. 1 to 3, the reflector is provided at its lower edge with widely spaced tabs or studs 21.

In accordance with the invention, the mouth 22 (FIG. 2) of the reflector 11 is located in a longitudinal plane which is oflset from the bulb axis A and is virtually coin- :ident with the longitudinal plane containing the first :air of support wires 4 and 5. It is supported from said vires 4 and by a rigid curved wire brace 23 which is ocated virtually in the said plane containing wires 4 1nd 5 and which is secured, preferably by welding, at its :nds to the tabs 21 and which extends across and is welded :o the respective support wires 4 and 5. In order to provide compatible metals for welding, the tabs 21 may be provided with eyelets 24 of a metal such as nickel for welding to a brace wire 23 of nickel-iron alloy, for example.

As compared to the previous standard construction described hereinbefore, the construction described above with reference to FIGS. 1 to 3 is much more rugged. The welding of the single length of brace wire 23 to the tabs 21 and support wires 4 and 5 puts the brace on a four point contact and on virtually the same plane as the tabs 21 and the reflector mouth 22. This restricts all sideward motion to a minimum and, together with the intermediate conductor 16 at the rear of the reflector, the assembly is rigidly mounted on the button stem 3. Furthermore, with a rigid construction of this type there is a greater dampening action produced in the lead wires, which minimizes filament oscillations under normal operating vibrations. The construction is also obviously simpler and less expensive than the prior standard structure. Moreover, by moving the reflector 11 forwardly from the bulb axis A and in alignment with the support Wires 4 and S, the pick-up angle of the projector lens is affected favorably to improve the optics of this system. The re flector cannot be moved forward in the prior standard construction because of the extreme sideward motion of the reflector when subjected to shock, along with the decreased space between the edges of the reflector and the glass bulb.

Referring to FIGS. 4 and 5, the same reference numerals have been applied to parts corresponding to those in FIGS. 1 to 3. In this case the means for supporting the reflector 11 from the support wires 4 and 5 is derived directly from the tabs 21:: which are moved closer together than in FIGS. 1 to 3 so as to be adjacent the said wires 4 and 5 and Welded directly thereto, or welded thereto through eyelets 24a, A' modification, not pertinent to the present invention, is that the ballast filament 17a is relocated behind the reflector and is connected between the rear end of inner lead wire 14 and the support and current supply wire 7 a portion of which is shown in FIG. 5 behind a broken away portion of the wire 6.

It will be evident that the species of FIGS. 4 and 5 possesses all the advantages of the species of FIGS. 1 to 3 discussed above, and results in a still further simplifcation by eliminating even the single brace wire 23. It will further be evident that the location of the reflector can be varied small amounts by, for example, welding the back sides of the respective tabs 21 or 21a to the front side of the brace wire 23 in FIG. 2 or to the front sides of support wires 4 and 5 in FIGS. 4 and 5; or the tabs, particularly tabs 24a in FIGS. 4 and 5, may be oflset small amounts either forwardly or rearwardly of the plane of the reflector mouth 22 and welded to either the front or the back sides of the support wires 4 and 5. It will also be evident that the outwardly extending ends of the support wires 4 and 5 might be omitted since they do not function as current supply conductors, but they are preferably provided for more secure retention of the lamp in its socket. It will also be evident that further changes, omissions and substitutions may be made in various details such as filament type and orientation, reflector type and shape, etc., within the spirit and scope of the invention as defined in the appended claims.

What We claim as new and desire to secure by Letters Patent of the United States is:

i 1. In an electric pnojection lamp comprising a tubular glass bulb having ,a glass stem sealed to the end thereof and at least four support wire members projecting into the envelope from said stem and arranged in first and second pairs located in planes extending longitudinally of and on opposite sides of the bulb axis, a concave reflector in said bulb and having its mouth in a plane extending V longitudinally of said bulb axis and offset from said bulb axis to be virtually coincident with the plane containing said first pair of support wire members, a single wire brace lying entirely virtually within the plane containing said first pair of support wire members and secured at it ends to spaced points at the lower end of said reflector and also extending across and secured at intermediate points thereon to respective ones of said first pair of sup port wire members, a filament at the front of said reflector, means electrically connecting said filament to respective ones of the second pair of support wire members, at least said second pair of support wire members also extending exteriorly of said stem as current supply conductors.

2. In an electric projection lamp comprising a tubular glass bulb having a glass stem sealed to the end thereof and at least four support wire members projecting into the envelope from said stem and arranged in first and second pairs located in planes extending longitudinally of and on opposite sides of the bulb axis, a concave reflector in said bulb and having its mouth in a plane extending longitudinally of said bulb axi and offset from said bulb axis'to be virtually coincident with the plane containing said first pair of support wire members, a single wire brace lying entirely virtually within the plane containing said first pair of support wire members and secured at its ends to spaced points at the lower end of said reflector and also extending across and secured at intermediate points thereon to respective ones of said first pair of support wire members, a filament at the front of said reflector, a pair of inner lead wires supporting said filament at its ends and extending through said reflector, intermediate conductor means connected between respective ones of said inner lead wires and said second pair of support wire members, at least one of said intermediate conductor means being a rigid wire supplementally supporting the said reflector, and at least said second pair of support wire members also extending exteriorly of said stern as current supply conductors.

3. In an electric projection lamp comprising a tubular glass bulb having a glass stern sealed to the end thereof and at least four support wire members projecting into the envelope from said stem and arranged in first and second pairs located in planes extending longitudinally of and on opposite sides of the bulb axis, a concave reflector in said bulb and having its mouth in a plane extending longitudinally of said bulb axis and offset from said bulb axis to be virtually coincident with the plane containing said first pair of support wire members, tab means extending from the lower end of said reflector to lie virtually within the plane containing said first pair of support wire members, said tab means spaced apart to be adjacent respective ones of said first pair of support wire members and secured directly thereto, a filament at the front of said reflector, means electrically connecting said filament to respective ones of the second pair of support wire members, at least said second pair of support wire members also extending exteriorly of said stern as current supply conductors.

4. In an electric projection lamp comprising a tubular glass bulb having a glass stem sealed to the end thereof and at least four support wire members projecting in the envelope from said stern and arranged in first and second pairs located in planes extending longitudinally of and on opposite sides of the bulb axis, a concave reflector in said bulb and having its mouth in a plane extending longitudinally of said bulb axis and offset from said bulb axis to be virtually coincident with the plane containing said first paid of support wire members, tab meansextending from the lower end of said reflector to lie virtually of said reflector, a pair of inner lead wires supporting 5 said filament at its ends and extending through said reflector, intermediate conductor means connected between respective ones of said inner lead Wires and said second pair of support wire members, at least one of said intermediate conductor means being a rigid wire supplemental- 1 1y supporting the said reflector, and at least said second pair of support Wire members also extending exteriorly of said stern as current supply conductors.

References Cited UNITED STATES PATENTS 12/1962 Peek et al 313315 12/1964 Scoledge et a1. 313113 JAMES W. LAWRENCE, Primary Examiner.

O R. JUDD, Assistant Examiner. 

1. IN AN ELECTRIC PROJECTION LAMP COMPRISING A TUBULAR GLASS BULB HAVING A GLASS STEM SEALED TO THE END THEREOF AND AT LEAST FOUR SUPPORT WIRE MEMBERS PROJECTING INTO THE ENVELOPE FROM SAID STEM AND ARRANGED IN FIRST AND SECOND PAIRS LOCATED IN PLANES EXTENDING LONGITUDINALLY OF AND ON OPPOSITE SIDES OF THE BULB AXIS, A CONCAVE REFLECTOR IN SAID BULB AND HAVING ITS MOUTH IN A PLANE EXTENDING LONGITUDINALLY OF SAID BULB AXIS AND OFFSET FROM SAID BULB AXIS TO BE VIRTUALLY COINCIDENT WITH THE PLANE CONTAINING SAID FIRST PAIR OF SUPPORT WIRE MEMBERS, A SINGLE WIRE BRACE LYING ENTIRELY VIRTUALLY WITHIN THE PLANE CONTAINING SAID FIRST PAIR OF SUPPORT WIRE MEMBERS AND SECURED AT 